Humidifier apparatus



April 3, 1956 M, A, POWERS 2,740,396

HUMIDIFIER APPARATUS Filed Feb. 2, 1953 im ,Z0 SLE) iinited States Paten@L ,Y

The present invention relates to an apparatus for humidifying air in a warmair furnacesystem".A More particularly, the invention relates to an arrangement for increasing the rate of 'humidication of air Without enlarging the capacity of' the humidifying apparatus.

In order to better understand the present invention it is believed it will be helpful if a brief description of the history of the developmental? humidier equipment is given.

The first humidifiers used many years ago in hot air furnaces consisted of castiron pans.locatedusuallyunder the firing door of the furnace but within the` heated air space connectedto the rooms to be heated'. This pan was filled manually and evaporatedwater slowly. Usually it` was drydue to lack of attention; Then came' the" automatic oat control chamber'whicli was sold as ari-accessory and usually installed by the customer or heating man. It was merely an automatic Water level maintaining device which was connectedtothe citywater supply and kept the old fashionedpan illediwithv Water, thereby making it much more effective.

Realizing theV very limitedwater evap'orating capacity of any device located'at a low levelin'the'furnace', the next step was to place the humidifying device'up high-in the plenum chamber, usually'just over the top of the furnace combustion chamber. Here" there was plenty; of; heat, water evaporatedrapidly, andin'mauy vcases during' cold weather when the furnace'wa'shiglily heated, water` actually boiled'frorn tlieghumidiiier: Under these circumstances there was no trouble in getting' enough evapora` tion, in fact, insome cases troubleoccurred dueto excessive vapor in the air stream; All" furnaces atithis period were of gravity type, that is', air oweditotheirooms by convection due tothe decreased weigl'ity ofthe hot' air. Air iiow areas in the furnace wererelatvelylarge, and the comparatively large bulk of," tlehumidifier` in` the plenum chamber didnotappreciably reduce the' flow of air through the system.

Next came the incorporation ofaforcedair hlower'to` the hot air furnace, the system now became dignified to the extent of being called a warm air furnace instead of a hot air furnace, and later this ywas further extended until now we call it a Warm air heating4 and airconditioning system, and as such it is quiteeffective andsatsfactoryinmillions of American homes. Oil andv gas-came to supply most of the heat, the. systemsbecame increasingly popular insrnaller homes, and smallautomatic warm air-systems now form the bulk of the homeheatingrmarket; These various factors workingtogether combined to setup-heat ing plant requirements of suchnature as to greatly restrict the designer of such equipment and this is the force which has ledito the present invention, aswillbe seen;

When power drivenqblowerswere-attached torfurn'aces to circulate heat, several conditions'arose-:in affectingthe applicationof ahumidier. First, `thedurnace',V in truth, became a Warm vair furnace, rather. than ahot airfurnace, due to the fact that the blowervsentvery largevolumes of air over the furnace, and that airusually uever'became very warm and seldom hot'even in severely cold weather. Consequently, evaporation from the humidifier was reduced, as evaporation requires 970' B. t`. u; or morefor each pound ofwate'r evaporated. Making' the humidifier pan larger to get niore'capacity'Was'impractical as *ity further impeded the'flow of air through the nowevenismaller plenum chamber around the furnace con'ib'uston chamber. This resulted in the widespreaduse of smallevaporating pans in the humidifier, plus the use oflVapoglas evaporating plates which tremendously increase theV evapcf rating capacity of a relativelyA small humidifier.` unitQ/suclifor example as they unit shown in th'ep'ate'nt to Botturn, No. 2,569,512'.

Generally speakingv such a' humidifier uses a pan of minimum crosssection to impede' the air flowto the leastl degree. The cross'placed'Vapoglas plates extend beyond the edges of the pan, but do not materially'restrict the air flow, while at thesame time serving most effectively to evaporate water` intoy the passing airstream. Such is the status of the' art nsofaras humidiiication is concerned inthe forced air furnace systems of today, but the'trends toward even smaller and more compact heating units'persist.

Thus, even though-the humidifier' apparatus of the type shown in the aforesaid PatentNo; 2,569,512 is extremely` eilcient in its operation, thereis still a'pr'essing need foi" improvements over the prior art' which'will permit' u-s'e" of a small humidifier unit tofulll'thevapor needs in'a'small or large home, depending on' how many Vapoglas plates are installed.

It is an object of the present invention to provideim'- proved apparatus for use in humidifyin'g air passing through' awarnrair furnace system, which apparatus is" constructedandiarrangedso that the p'atl'i'offlow ofdry warmy air' is directed; acrossy the evaporator elements to obtain the' optimum rate of humidiiicatio'n of'fsuch'" air', therebyr ,permitting the use` of smaller humidifere'quipe' menti than was possible witlithe' prior art'devices;

It" ist still another: object of thev presenti' invention"y tol provide in a Warm air furnace system animproved"liu'n`1idil` tier apparatusI ofthe foregoing character which system is constructed and arranged soZ that" the" blower tliere'off dise charges its dryair ontotlie evaporator-'elements of tle humidifierunit: softhat optimum-*evaporationi's obtained? Other objects ofthisinvention will appear in' tliefol following description yand appended claims, reference being! hadI to Ithe accompanying' drawings' forming; a part' o'fltliis` specification wherein likel reference characters designate" corresponding partsY in the" several views.

In f thedrawings:

Fig. lis a vertical sectional'view showing one' embodi-` mentof the presentirivention wlie'rein ythe huniiclterJ unit is'mounted in the plenumchamber ofi the furnace"ins'u'cln manner that warm air is directedbetween'tite-evaporaL tor elements of the unit; and i Fig. 2 is an enlarged-sideviewof thehum'idiiierunit Before explaining the 'present invention in detail, it is'to beunderstood that the invention-isnotlimited in'it'sap-v plication to the details of construction and ar'rang'errien'tc of partsiiliustrated in the accompanyingtdra'wings, since` the invention is' capable of other' embodimentsand offbeirigg practiced or carried'outin vario'sw'ays. Also, it is ftofb'e" understood that the plirase'olgyoirterminology 'employedf herein -is` for the pu'rpose'of' description and" notoflimita` tion.'

Gne embodiment of. the.' present vinventioni is" shown by way of example in Fig. i, wherein .alconveutionalhhua' midifier unit, such' asiskshown in` greater detailinfFgbZ, isf employed. This humidifier: unit includes -a= float t tank? likwhich is l connected i to Ian evaporatorf pan-y 12 by? the water conduit- 14;.l Water: isfsuppiiedl tofthewoattank: 10.1 through f the water inlet conduit 16, Yandthe rate?"r off: owf" of this water is regulated by any conventional water level regulating means which will maintain the water level 18 within the evaporator pan 12 essentially constant regardless of varying rates of evaporation. Since the water level regulating means forms no part of the present invention it will not be shown nor described, but reference is made to the aforesaid patent to Bottom, No. 2,569,512 for a disclosure of one type of water level regulating means that may be used with the present invention.

Mounted within the evaporator pan 12 are a plurality of evaporating plates 20, which, as previously explained, tremendously increase the evaporating capacity of the humidier unit. A more complete description of these evaporating plates 20 can be found in my prior patent, No. 2,271,829, granted February 3, 1942.

An arrangement which embodies the principles of the present invention can be seen in Fig. l. Here the evaporating pan 20 and the evaporating plates 12 are mounted within the plenum chamber a which is disposed below the heat exchanger 24a. by the blower which has its discharge outlet extending through the top of the furnace wall 26a so that air can be directed onto and around the sides of the heat exchanger 2da to the plenum chamber 30a below. The air entering the plenum chamber 36a will ow over and between the evaporating plates 20. This humidilied air will then be discharged through the duct 32a.

lf desired, still other embodiments of the present invention may be employed. For example, the humidifier unit can be above the heat exchanger illustrated in Fig. 1, where the airwill pass over the unit before entering the heating zone. From a practical point of view this upper location is often best because it can be more easily inspected and serviced than below the furnace.

From the foregoing descriptions of different embodiments of the present invention, it can be seen that one of the important features of the present invention is that the air which flows through the furnace is directed so that it flows downwardly toward the water in the evaporator pan 12 and between the evaporating plates 20. The improved operation of the humidifier unit which results from this change and reorientation of parts is very startling and unexpected.

As explained earlier, in very small furnaces with relatively high air dow velocities, any unit such as a humidier, while small does tend to restrict the air ow past it. The standard evaporator pan which is conventionally used is three inches wide and about twelve inches long, the smallest possible for a reliable unit of sutiicient evaporating capacity to fulfill the vapor needs in a small or large house, depending on how many evaporating plates are installed. A careful study of the air ow as it passes from below upward around the pan proper and between the evaporating plates of the prior conventional structures, shows that the airstream is diverted sideways by the interference of the pan, and consequently, it is now discovered that the humidifier unit is not as effective as it might be if the air stream could pass over the evaporating plates unimpeded by the bulk of the pan.

In working toward a solution of the problem of eliminating the pan as an obstruction to air flow, the principles of aerodynamics were applied and the airow was reversed from the conventional bottom-to-top flow to a top-tobottom ilow. This had the effect of eliminating the relatively stagnant air pocket which was discovered to exist above the evaporator pan and between the evaporating plates when the conventional bottom-to-top ow was used. The evaporation was then materially increased because more relatively dry air had an opportunity to flow between the plates and scrub the same.

Actual airow tests with a standard humidifier unit of the type shown in the aforesaid patent to Bottum, No. 2,569,512, equipped with 10 evaporating plates were made using the conventional bottom-totop ow and the top-tobottom ow. The results obtained from these tests clear- Air to be warmed is supplied ly demonstrated the superiority of the present invention over the prior art arrangements. In conducting these tests the air temperature and humidity were substantially the same, and the rate of air flow and the duration of the tests were the same. During two hour tests the total evapo ration when using the conventional bottom-to-top ow was 7.5 oz. of water; whereas, when using the top-to-bottom flow of the present invention, 11.4 oz. of water was evaporated` Thus, an increase of 52% in effectiveness was obtained when using the teachings of the present invention, and as a result it is now possible'to reduce the present humidiiier units by one-third in size and maintain present capacity. This means still further 'reduction of the unit as an obstruction in the airstream.

Having thus described my invention, I claim:

l. In combination with a furnace having a heat exchanger therein and having a plenum chamber below the heat exchanger and means forming an air passage through which air can be passed from above the furnace downwardly around and in heat exchange with the heat ex' changer and thence downwardly to the plenum chamber, said plenum chamber having an outlet from said furnace,

an open pan type humidifier unit mounted in said plenum chamber in the nonnal path of downwardly directed heated air and having its open portion facing upstream of said path, the pan of said humidifier unit supporting a plurality of evaporating plates in. an upright position, said plates having their lower ends adjacent the bottom of the pan so as to be immersed in water carried by the pan, the upper portions of the plates extending beyond the confines of the pan into the normally heated airstream path for transferring moisture to the air, said platesbeing formed from a relatively rigid porous material to effect capillary action.

2. ln combination with a furnace having a heat exchanger therein and having a plenum chamber below the heat exchanger and means forming an air passage through ing beyond the contines of said pan, said pan beingy mounted within said plenum chamber in the normal path of downwardly directed heated air and having its open portion facing upstream of said path so that the owing air will pass between the upper portions of said evapo-l rating plates, the latter being formed from relatively rigid n material which is porous so as toetfect capillary action for transferring water from said pan to the air flowing between the plates, and a blower for blowing air past said heat exchanger and between said plates.

References Cited inthe le ofv this patent UNITED STATES PATENTS 1,175,069 Mackey Mar. 14, 1918 1,362,932 Engleman Dec. 2l, 1920 1,817,357 Fisher Aug. 4, 1931 1,866,650 Hill July 12, 1932` 1,870,460 Lambert- Aug. 9, 1932 1,984,866 Day- L Dec. 18, 1934 1,989,228 Criqui lan. 29, 1935 2,047,767 Byrd July 14,'1936 2,128,245 Hager Aug. 30, 1938 2,155,070 Woolley Apr. 18, 1939 2,271,829 Powers Feb. 3, 1942 2,361,545 Higley Oct. 3l, 1944 2,377,527 Siefkin .iune 5, 1945 2,503,002 Shreve Apr. 4, 1950 2,569,512 Botturn Oct. 2, 1951 y2,620,780 Mueller. Dec. 9, 1952 

